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  • Hey it's me Destin.Welcome back to Smarter Every Day. We're right in the middle of a

  • series on helicopters and we're gonna talk to you about.. What is this called? (son) Parachute.

  • A parachute. So in airplanes, the pilot

  • can have a parachute so if anything goes south he can jump out

  • and he can parachute to safety. Do you want to test the parachute real quick?

  • (son) Yeah I'll do it. OK we're gonna use the parachute off the balcony here. Check this out.

  • Daddy's gonna throw it. You ready?

  • Parachute man...

  • in the ocean. 1...2...3...

  • Oh man! [laugh]

  • We just gave the parachute man to our neighbours.

  • So think about this. Let's say we're in a helicopter

  • and we're up high and all of a sudden we run into trouble when we run out of engine power

  • and we start to fall. So we've got this weight and it's

  • suspended by this rotor system. Now if we're smart about it we can

  • change the pitch on our blades to spin up our rotors really really fast.

  • And then we have kind of like a pinwheel or a windmill effect.

  • And if we're really smart, right at the last minute, right before we hit the ground,

  • we can change the pitch on those blades to provide lift. So we're

  • back driving our rotors and then right at the last minute we're using them to

  • decelerate, right before we hit the ground. This is a manouver called autorotation,

  • and this has kept helicopter pilots alive for many many years.

  • In fact, they've even done autorotations from 40,000 feet.

  • So a helicopter basically has a built-in parachute. But with a helicopter you've got this

  • rotating disc right in front of you. So my question is, what happens if you lose power

  • at altitude. So this battery he just put in, what if it dies. So what happens Carl?

  • (Carl) If you lose power in a helicopter you can autorotate. Alright.

  • So Carl's gonna demonstrate autorotation and we'll get an idea for what happens.

  • You're getting Smarter Every Day.

  • Alright so what exactly are we about to do here?

  • (Carl) We're gonna demonstrate autorotations. I'm gonna take you up a couple of hundred feet up in the air

  • shut the motor off, and fly it all the way to the ground without power.

  • (Destin) Sounds like a genius idea to me. (Carl) [laughs] Let's do it.

  • (Destin) You know... This is expensive right? (Carl) Yeah

  • [ rotor noise ]

  • Alright so where you at? How high?

  • (Carl) Aah this is probably about 300 feet. Three and I'm gonna

  • turn the motor off right now, and we're coming in without

  • power. (Destin) On a very expensive helicopter. (Carl) Oh yeah. (Destin) So there's no power right now.

  • (Carl) No power at all.

  • (Destin) So why did that happen?

  • What did you just do? (Carl) We're turning the pitch of the blades down,

  • and as the helicopter is falling down, the air being forced through by gravity

  • spins the blades. (Destin) So it's like a windmill? (Carl) It's like a windmill. (Destin) So helicopters are

  • a whole lot safer than I thought. I'm gonna be honest with you I'm not very impressed though cause

  • it was right side up the whole time. [laughs]

  • (Carl) Let's do it upside down. (Destin) W..w..wait dude. I'm joking dude.

  • (Carl) Aah. Let's do it! (Destin) He can do it. (Carl) Let's do it!

  • I am not responsible for what's about to happen.

  • [rotor sounds]

  • You don't have to do

  • it if you don't want to. (Carl) [laugh]

  • (Destin) Are you upside down already? (Carl) Oh yeah.

  • (Carl) Here we go. We're gonna flip upside down.

  • (Destin) So you have an unpowered.. (Carl) Power is off (Destin) helicoper upside down. (Carl) Correct.

  • (Destin) This makes perfect sense. Holy cow.

  • [laughs]

  • (Carl) There we go. (Destin) That is messed up man. Alright so helicopters are

  • a whole lot safer than I thought, and if you want to see more about how they work

  • look at this video series that we're making, how to control helicopters. This is Carl.

  • I put his info in the description. Please subscribe. Later. Where's my thinking hat?

  • I need my thinking hat. [laughs]

  • [ Captions by Andrew Jackson ]

  • Captioning in different languages welcome. Please contact Destin if you can help.

Hey it's me Destin.Welcome back to Smarter Every Day. We're right in the middle of a

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ヘリコプター物理学シリーズ - #5 オートローテーション=NO PARACHUTE!- スマートな毎日50 (Helicopter Physics Series - #5 Autorotation = NO PARACHUTE! - Smarter Every Day 50)

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    林宜悉 に公開 2021 年 01 月 14 日
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